1. Field of the Invention
The present invention relates to an in-cell touch display device.
2. Description of Related Art
In response to the development of the information society, there is an increased demand for various types of display devices able to display images. Currently, various display devices, such as liquid crystal displays (LCDs), plasma display panels (PDPs) and organic light-emitting diode (OLED) displays, are used.
Many display devices provide a touch-based input system enabling users to intuitively and conveniently input information or instructions directly to a device screen, rather than using conventional input systems, such as buttons, a keyboard and a mouse.
In order to provide such a touch-based input system, sensitivity to the touch of a user and the ability to accurately detect coordinates of a touched point are required.
For this, in the related art, touch sensing is provided using a touch sensing method selected from among a variety of touch sensing technologies, such as resistive touch sensing technology, capacitive touch sensing technology, electromagnetic induction technology, infrared (IR) touch sensing technology and ultrasonic touch sensing technology.
Among the variety of touch sensing technologies, capacitive touch sensing technology is popular. This technology uses a plurality of touch electrodes (e.g., row electrodes and column electrodes) formed on a touchscreen panel to detect a touch and coordinates of a touched point based on a change in the capacitance between touch electrodes or between a pointer, such as a finger, and a touch electrode.
According to the capacitive touch sensing technology, in addition to capacitance necessary for touch sensing, undesirable parasitic capacitance is generated by other voltage lines or electrodes surrounding touch electrodes.
The undesirable parasitic capacitance causes certain problems, for example, increasing the load of a touch operation, lowering the accuracy of touch sensing, and in severe cases, making touch sensing impossible.
The problems caused by such undesirable parasitic capacitance frequently occur in in-cell display devices inside which a touchscreen panel (TSP) is integrally provided using “in-cell” technology.